Case Studies of IR Based Rapid PC Motherboard Failure Analysis

摘要

From the testing performed with the IR thermography system, the following could be concluded: 1. The associated savings in time using the thermography system easily justified the cost of the system. In addition, the system allowed more effective identification of desired failure modes for further analysis ultimately reducing the time to root cause of an identified issue. 2. The IR thermography system was successfully applied to identify and locate components with internally resistive failure modes exhibiting an identifiable thermal image. It was also effective in identifying and locating power plane related resistive failures. 3. The IR thermography system was very effective in large volume screening for known failure conditions. It eliminated the uncertainty of selecting valid samples within a date code range of suspected defects. The sample quality and confidence level was dramatically improved; focusing the RCFA effort on verified defective components. 3. The thermography system was less effective in identifying solder defects and broken/defective traces due to the absence of consistent thermal signatures. 4. When absolute values were measured, the emissivity of the investigated object became important. The proper emissivity correction had to be applied to ensure accurate temperature measurements with an IR thermography system. Absolute temperature measurements on objects consisting of multiple different materials were not viable due to the multiple emissivity corrections that had to be made. A disadvantage of the thermography system profile was the low resolution of the detector, 160 x 120 pixels. It was challenging to identify small components when a large circuit board was thermally imaged. The thermal camera needed to be housed in an enclosure to prevent any thermal influences distorting the thermal image. The user should be aware that heat reflected from the IR camera, if not accounted for, may distort temperature measurement results, especially on aluminum surfaces like electrolytic capacitors. Graphic image software assisted in identifying possible defective areas that needed further investigation by highlighting these areas. Image overlay was rather cumbersome compared to image subtraction.